RADIUS, which stands for "Remote Authentication Dial In User Service”,
is a network protocol - a system that defines rules and conventions for
communication between network devices - for remote user authentication
and accounting. Commonly used by Internet Service Providers (ISPs),
cellular network providers, and corporate and educational networks, the
RADIUS protocol serves three primary functions:

* Authenticates users or devices before allowing them access to a network
* Authorizes those users or devices for specific network services
* Accounts for and tracks the usage of those services

FreeRADIUS is a modular open-source implementation of the RADIUS protocol
featuring numerous authentication types, including Extensible Authentication
Protocol (EAP), support for virtual servers and more.
